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Laxmikanth Kankipati, John K. Johnstone, Christopher A. Girkin; Changes In Lamina Cribrosa Depth In Response To Increased Intraocular Pressure In Subjects With No Ocular Disease. Invest. Ophthalmol. Vis. Sci. 2011;52(14):6255.
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In response to raised intraocular pressure (IOP), there is antero-posterior displacement of the Lamina Cribrosa (LC) in monkey models (Sigal 2010). The present study looked at the changes in the LC depth in response to raised IOP in human subjects without ocular disease using Spectral Domain Ocular Coherence Tomography (SDOCT).
We raised the IOP in normal human subjects without ocular disease to 30 mm Hg with an Ophthalmodynamometer, while imaging their eyes with SDOCT. Delineation of the OCT images was done using Devers Eye Institute Multiview software in 24 sagittal sections (Downs 2007). A best fitting ellipse was computed using principal component analysis to define Bruch’s Membrane Opening (BMO) and this was taken as a reference for further analysis. A mesh was reconstructed from the point cloud for the anterior surface of LC and Internal Limiting Membrane (ILM). We then measured the distance from a uniform sampling of the BMO ellipse to the LC mesh and ILM and calculated the mean and maximum depths for the LC (LCD) and the cup depth (BMO-ILM).
BMO ellipses did not change with IOP elevation (n=4, p>0.05). However, the mean and maximum LC depths were significantly shallower when the IOP was raised when compared to normal IOP measurements (Table 1, n=4, p<0.05) and returned to baseline within 5 minutes. There was no significant change in the cup depth with increased IOP (n=4, p>0.05).
We report that there was a significant shallowing in the LC depth in response to acute transient elevation of IOP in people with no ocular disease. These techniques may provide a potential method to evaluate deformation of the LC with in-vivo imaging.
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